The equation of aircraft loading coefficient variable is obtained from the equation of aircraft motion, where the aircraft bump is mainly determined by the vertical wind velocity of the atmosphere. The characters of lee rotors, the high-level turbulence and low-level turbulence generated by flow over mountain are investigated using the numerical model ARPS. The results show that the critical layer and surface friction play a significant role in the forming of the rotors and reversal flow, and the high-level turbulence in the troposphere and low-level turbulence in the lee of the mountain. This is why the airplanes flying over the mountain region often meet with the strong flight bump, and the effect of mountain on the atmospheric turbulence and flight bump is very important and dominant over other factors. This helps to understand the mechanism of flight bump and improve the forecast of the aviation flight meteorological conditions.